Sharpening a chisel with a bench grinder

Photo 1: Square off the edge

Grind the front edge of the chisel at 90 degrees to the
face of the wheel to remove chipped or rounded edges.
Apply light pressure and don't overheat the blade. Keep
your tool rest within 1/8 in. of the grinding wheel.

Removing nicks

It's easier to square off a bad edge first so you have a straight edge to follow when you hold the chisel against the grinder.

Photo 2: Flatten the back

Remove any round-over or nicks on the backside
of the chisel blade by rubbing in a circular
motion. Flatten the back of the blade with
300-grit wet/dry sandpaper taped to a 1/4-in. section of
plate glass. (Check with local glass companies for small, scrap pieces.)

Photo 3: Sharpen the edge

To sharpen the edge, slide the
chisel from right to left and back
again with the rest set at 25 to 30
degrees (match your original angle). Skip
this step if the edge is just dull, not uneven.
Make sure the edge stays perpendicular to
the grinding wheel. Check the blade with a
square to make sure you're grinding the
edge exactly perpendicular to the sides of
the blade.

Photo 4: Clean off burrs

To sharpen the edge, slide the
chisel from right to left and back
again with the rest set at 25 to 30
degrees (match your original angle). Skip
this step if the edge is just dull, not uneven.
Make sure the edge stays perpendicular to
the grinding wheel. Check the blade with a
square to make sure you're grinding the
edge exactly perpendicular to the sides of
the blade.

Check the polish

The back of the chisel should show an even polish when you're done.

Photo 5: Create a secondary edge

Hold the sharpened primary bevel flat to
the medium-grit stone, then raise it
about 3/8 in. near the back of the
handle as shown. Memorize this angle
and move the blade forward and back along
the stone to create a secondary bevel.
Lubricate the stone as necessary to help flush
away any minute metal filings. After several passes,
repeat both the previous step and this step using a
fine-grit stone until you have a super-sharp secondary edge.

Finished edge

The secondary bevel should look like this.

Some carpenters and woodworkers
spend hours in search
of the perfect edge, painstakingly
hand-sharpening from one
grit stone to the next. While that
process may be necessary for some
tasks, most projects require a speedier
fix. In this article, you'll learn
how to quickly fix a chipped edge
and then reshape and sharpen it—all in about 10 minutes per chisel.

You'll need a bench grinder with
a 100-grit wheel, some wet/dry
sandpaper, a sharpening stone
(with one medium side and one
coarse side) and a lubricant.
Follow our step-by-step photos to
get a good sharp edge on your
chisel, and if you're unfamiliar with
your grinder, follow the safety steps below before you begin. If you've
never used a grinding wheel before,
practice this technique on one of
your least-favorite chisels first.

Keep Your Tool Cool

Dunk the blade in water every two
passes (three to four seconds) to keep
the blade from burning. A straw or
bluish color means you've overheated
your chisel and ruined the temper. Practice
with your least-favorite chisels first.

Dressing your wheel

Dresser in use

Hold the dresser against
the grinding wheel until the
wheel edge is flat and free
of debris.

A clean, well-dressed
wheel
is more efficient
and less likely to burn
the edge of your tool.
Dress your grinding
wheel to remove particles
embedded in the wheel and
to reshape it. Look for these
special tools at hardware or
welding supply stores. You
can also find them online. (One type is the Grizzly H5944 Wheel Dresser #0, available through our affiliation with Amazon.com.)

Not All Grinding Wheels Are Created Equal

You can use two kinds of
aluminum-oxide wheels to
sharpen your chisels; one
is blue-gray and the other
white. We used the darker-color
wheel, which is harder
and will keep its shape
longer. The drawback, however,
is that it grinds hotter
than the softer, white wheel.
Too much heat will weaken
the steel. The soft wheel will
need more frequent shaping
with a dressing tool, but
you'll be less likely to burn
the edge of your chisel while
grinding. For best results,
use a 100-grit wheel to
shape your chisel blades.